• Change mmap() to fail requests with EINVAL that pass a length of 0. This behavior is mandated by POSIX.
• Do not fail requests that pass a length greater than SSIZE_MAX (such as > 2GB on 32-bit platforms). The 'len' parameter is actually an unsigned 'size_t' so negative values don't really make sense.

Submitted by: Alexander Best alexbestms at math.uni-muenster.de
Reviewed by: alc
Approved by: re (kib)
MFC after: 1 week